Lubricating oil



partly oxidized e oil,.and

Patented Dec; 7, 1943 UNITED .s'r

LUBRICATING on.

Elmer W. Cook, New York, N. Y., and William D.

Thomas, American N Drawing This invention relates to improved oils,particularly lubricating oils of the crankcase type. Althoughlubricating oils oi. the present inven tion are highly desirable for usein crankcases of passenger automobiles they are especially valuable forheavy duty use in truck, bus. aeroplane, marine and Diesel engines whichoperate for long periods of time at high temperatures.

The principal objects of the invention are to provide a lubricating oilof ,the heavy duty type In, Stamford, Conn., assignors to d Company, N.Y., a corporation of Maine Application May 16, 1942, erial No. 443,307

which is resistant to oxidation and sludge forperiods of time, asinheavy duty service, they tend to decompose with the formation ofcomplex-and objectionable oxidation and decomposition products. Underthe high temperature con- 1 ditions prevailing in the engine thesedecomposition products polymerize to form lacquer-like deposits on orbetween the moving parts causing these parts to stick. Even largerquantities of polymerization products remain dispersed in the v arereadily precipitated to form a sludge when'the i cools or when fresh oilis added to the heated metal surfaces and cut down. the eflective lifeor the en ine.

A number of oil soluble detergents oi the type oi metal soaps,phenolates and aicohoiates have These precipitated sludges becomeaskedon been proposed and used in crankcase oils to dis-I solve or dispersethe sludge and prevent lacquer deposits and stuck piston rings.Unfortunately,

however, the great maiority 01 these substances increase the rate ofoxidation and their presence results in an increased concentration ofacidic.

oxidation products in the .oil. Increased quantitles of these acidicoxidation products. in the oil create'in turn aneve'n more serious.difficulty for they attack and corrode alloy bearings commonly employedin internal combustion engines. Alloys composed of copper-lead,silver-cadmium. nickel-cadmium. etc. are widely-used and are subject toattack by the acidic oxidation prod ucts iormed in the oil. 7

Certain anti-corrosion agents which have no detergent properties, havebeen added to lubrieating oils in order to counteract the corrosiveeflect of the oxidation .products of the oil. Although many of thedetergents and anti-corrosion agents which have been previouslymentioned perform their individual functions in lubricating oils the twoseparate additives do not cooperate-to produce a satisfactoryanti-corrosion and detergent action when used together. The function ofa corrosion inhibitor is to cover the bearing surfaces and othercorrodable parts of theengine with a passivating film that preventscorrosion of the metal by the organic acids and other corrosive productsof the oil.- A detergent, as its name implies. operates to removeadhering solids in the metal parts of the engine and thus produce aclean metal surface. Consequently mixtures of detergent with acorrosion.

.inhibitor have proven to be ineflective over-any extensive period oftime since the deternt action of the sludge inhibitor tends to removethe corrosion inhibitor from the metal suriacethusf rendering itineffective for the purpose intended.

sulfides and salts thereof avoid the above-described difliculties by e ai notonlyexcellent corrosion inhibiting properties but detergentcharacteristics, thus enabling us to provide a' lubricating oil having a1 e additive eflective to inhibit corrosion, sludge and v forma-.

tion, ring sticking and other cuities ienced with lubricating oils-s ina heavy duty capacity. These compounds are also extremely heat stableand are not decomin the-oil at the high operating temperaoitenencountered. They are also practicallywater insoluble and are notextracted from the oil by contact with water nor do they tend to promotethe formation of emulsions with water in the oil.

Another advantage to be obtained by our use of bis-(ZA-dialkyi phenol)-e-alkyl phenol sulfides or their salts lies in their soiubilizingaction on certain materials whichare known to be good detergents,anti-oxidants, etc. or have good corrosion inhibiting properties butwhich cannot ordinarily be used because of their oil-insolubility.Certain dithiophosphates, such as di-(p-tertiary Y amylphenol)dithiophosphate; calcium. barium. aluminum, zinc and magnesiumstearates. palmitates. naphthenates, etc. are diflicultly soluble inlubricating oils but'because of their solubility in the compoundsdescribedherein it is possible to The bis-(ZA-dialkyi phenol) -d-alisylphenol ciently large to be effective.

The bis-(2,4-dialkyl phenol) -.4alkyl phenol 1 sulfides and saltsthereof employed by us in preparing our improved lubricating oils arenew chemical compounds and may be represented by the general formula:

i. i .L l J.

in which R, R1 and R2 are alkyl radicals, n is the small whole number 1or 2 and m is the small whole number 1 or 2, Me is hydrogen or a salt--vforming radical and X is the valence of Me. These compounds aredescribed and claimed in our copendin-g application, Serial No. 443,306,

filed May 16, 1942.

The bis-(2,4-dialkyl phenoD-4-alkyl phenol sulfides and salts thereofillustrated by the general formula above may be prepared by reactingmixtures of 2,4-dia1kyl phenols and 4-alkyl phenols with sulfurdichloride (S012) or sulfur monochloride (S2012) depending upon the typeof sulfide desired as the reaction product. The salts of these compoundsmay be prepared from the re sulting reaction product as ll be describedhereinafter.

When reacting two molecular proportions of 2,4-dia1kyl phenol with onemole of 4-alkyl phenol and sulfur dichlorida'for example, bis-(2,4-dialkyl phenol) -4-alkyl phenol dithio ether is formed as follows:

' 0H 0H t J J 2 2801, --e

x a I OH- on on R s s a O Q U 4H0! T l V a 4 l When using 2 moles of2,4-dialky1 phenol mixed with 2 moles of 4-alkyl phenol with sulfurdichloride the reaction proceeds in the same way but with the formationof bis-(2,4-dialkyl phenol)- dl-4-alkyl phenol trithio ether, a compoundhaving four aryl groups, as follows: a

I 0H 0H 0H 0H S R O UT) O R; a a 1 and them to oils in this way inamounts sufll- When sulfur monochloride is substituted in place of thesulfur dichloride the aryl groups are bound together with two sulfur-atoms,--SS-, and n in the general formula above becomes 2'. Thesecompounds possess similar properties to those inwhich a'single sulfuratom links the different aryl groups and are also valuable in ourimproved lubricating oils.

In preparing these new compounds it is convenient to dissolve thevarious reactants in an inert solvent such as carbon disulfide, carbontetrachloride, petroleum naphtha, ethylene dichloride, chlorbenzene,chloroform or the like. Merely mixing together the various reactants inthe desired molecular proportions will cause the reaction to be broughtabout. No catalyst is ordinarily necessary. The reaction vessel shouldbe fitted with agitating means and means for removing the HCl liberated.Towards the end of the reaction when the evolution of HCl has slowedconsiderably the preparation may be completed by heating the reactionmass to 50-60" C. for a few minutes to expel most of the remaining HCl.The product may then be washed with a dilute alkaline solution to removetraces of the acid. In

the event that the material tends to emulsify during the washing stepthe addition of a small amount of butanol will help preventemulsification. After washing the excess solvent may be.

by evaporation under salt with a desired metal salt such as, for ex-.

ample ZnClz, SnClz, A1013, etc. Metal salts of these compounds may alsobe prepared by reacting the compounds'just described. withappropriatemolecular amounts of finely powdered metallic aluminum, metallicmagnesium turnings calcium metal, etc. A small amount of mercur chloridemay be added to start the reaction. The

reaction mixture may be gently heated on a steam bath at first but mayrequire cooling later becaus of the exothermic character of the reactionMetal salts may also .be preparedby heating the compounds described withan alcoholate of a lower boiling alcohol, sodium methylate or aluminumbutylate, for example, under conditions such that the lower alcohol isdriven off.

The preparation .of the bis-(2)4-diamyl phenol)-4.-amyl phenol dithioether will now be described. In this preparation 2,4-diamyl phenol isreacted with 4-amyl phenol and sulfur dichloride. As will be apparent wemay. use other 2,4-dialkyl phenols with other 4-alky1 phenols in thepreparation of these new compounds. The various alkyl groups R, R1 andR2 in the general formula above may be all the same or may be alldifferent.

In this way it is possible to control the viscosity and oil solubilityof the resulting compound. For ood oil solubility compounds employedshould have at least one, preferably: more, alkyl groups .of from 4 to14 carbon atoms.

01 the various 2,4-dialkyl-phenols which may be employed by us may bementioned 2,4-diamyl phenol, 4-tertiary butyl ,orthocresol, 2-dodecyl-4-tertiary amyl phenol, 2,4-di-tertiary butyl phenol,2-buty1-4-isopropyl phenol, 2-butyl-4-amyl phenol, 2-isopropyl-4-octylphenol, etc. As 4-alkyl phenols we may use those such as p-cresol,4-isobutyl phenol, l-tertiary amyl phenol, 4-ethyl hexyl phenol, 4-octylphenol, andthe like. As

' will appear from what has been said before with one. or two therelative amounts of the 2,4-diallwl phenol and 4-alkyl phenol can varyconsiderably depending upon thetypeof product desired. Ordinarily twomolecular proportions of the 2,4--dialkyl phenol preferred.

' Example 164 parts by weight of p-tertiary amyl phenol and 468 parts byweight of 2,4-di-p-tertiary amyl phenol were dissolved in 260 parts byweight of benzol. 205 parts by weight of sulfur dichloride was thenadded to the solution with stirring, the

temperature being maintained below 40 0. As

7 soon as all the sulfur dichloride had'been added the mixture waswarmed to 50-60 C. for 10 minutes to complete the reaction and expelmost of the HCl. The reaction mixture was then washed with warm dilutesodium carbonate solution to remove dissolved hydrogen chloride.

The washed reaction product was then heated under reduced pressure toremove the benzol. Bis-(2,4-diamyl phenol) -4-amy1 phenol .dithio etherwas obtained as a brown viscous product.

'. The barium salt of this product was obtainedby dissolving 60 part byweight thereof in 80 parts by weight of aromatic petroleum naphtha and40 parts by weight of 95% alcohol. 41 parts -by' weight of finely groundBa(OI-I)2.8H:O was added and the mixture heated and solvents and waterboiled ofl. More naphtha was added from.

time to'time to replace that lost by evaporation. When the temperaturehas "reached 125-135 C.

the neutralization was substantially complete and all of the water hadbeen expelled. The solution was then diluted with naphtha and aftercooling filtered from traces ofinorganic bariumalts. The solvent wasthenremoved by evaporation under reduced pressure. The product was astiff viscous dark-colored liquid, easily oluble in light paraflin baselubricating oil. v

If desired lubricating oil may be added to the product before all of thesolvent has been removed by evaporation. This step facilitates blendingof the oil with the additive and enables us tq. obtain a productcontaining 50-80% or more, of the additive suitable for sale and dis--tribution to the trade for blending purposes.

or the various bis-(2,4-dialkyl phenol) -4-alkyl phenol sulfides whichmay be employed by us we prefer to use the alkaline earth metal saltsand particularly those salts in which the alkyl groups are of from 4 to14 carbon atoms in length. These compounds are so very eflective that itis possible to improve lubricating oils to a great extent by the use ofvery small amounts of the compound. In lubricating oils intended forordinary purposes where high temperatures occur only occasionally, from0.1-.08% of the bis- (2,4-

dialkyl phenol) 4-alky l phenol sulfide is sub} ficient. In an oilintended for heavy duty service it is generally advisable to Ease alittle more, as for example 0.54% in theoifi The effectiveness of thebis-(2,4-dialkyl phenol) -4-alkyl phenol sulfides in lubricating oils ascorrosion inhibitors, detergents and anti-oxidants is demonstrated bythe following results obtained by subjecting a S. A. E. solvent refinedPennsylvania oil containing 0.5% by weight of the barium 'salt ofbis-(2,4-diamyl phenoD-4- amyl phenol dithio ether to the standardUnderwood oxidation test. A sample of oil containing 0.5% of the bariumsalt of bis-(2,4-diamyl phenol' -di-'4-amyl phenol trithio ether and a,control sample containing no additive were also tested moles of the4-alkyl phenol is L l l- I at the same time. The test consisted inheating 1500 cc. of the oil at 325 C. and continuously spraying aportion of the hot oil against a 3" x 10" freshly sanded copper 'bailleand two -5 freshly sanded bearings to be tested for corrosion for 5hours while permitting free circulation of air during the heatingperiod. Samples of the oxidized oil were then examined for A. P. I.

gravity. neutralization number and the bearings 10 were examined forweight loss due to the effects The neutralization number indiofcorrosion. cates the fomiationof acidsresulting from oxidation of theoil. The A. P. I. gravity also indicates the decomposition in the oilduring the test, 15 the lower values indicating a greater degree ofdecomposition. Results wereas follows:

Underwood oxidation test The results of these tests clearly ShOW theantioxidant and anti-corrosion properties of oils treated with ournew-bis-(2,4-dialkyl phenol) -4'- alkyl phenol sulfides.

.What we claim is: g 1. A lubricating oil composition containinglubricating oil and small amounts of a compound having the generalformula in which R, R1 and R2 are alkyl radicals, n is a small wholenumber less than 3, m is a small whole number less than 3, Me is ametal, and x is the valence of Me.

bricatihg oil and 0.1-3.0% of a compound having the general formula inwhich R, R1 and a: are sum radicals, at least one of which has from 4 to14 carbon atoms, n is a small whole number less than 3, m is a smallwhole number less than 3, Me is a metal, andxis' the valence of Me.- 73. A lubricating oil composition containing inbricating oil and smallamounts of acompound having the general formula 2. A lubricating oilcomposition containing luin which 3,81 andRsare alky l radicals, nisasmall whole number less than 3, Me is a metal, and X is the valence ofMe.

4. A lubricating oil composition containing lubricating oil and smallamounts of a compound having the general formula t I ,t

I t A A in which R, R1 and Rs are alkyl radicals, Me is a metal,-and xis the valence of Me.

6. A lubricating oil composition containing lubricating oil and (Ll-3.0%of a compound having the general Iormula ,1 R1, LQIQF in which R, R1 andR: are alkyl radicals, at least one oi which has from 4 to 14 carbonatoms, n is a small whole number less than 3, m is a small whole numberless than 3, Me is an alkaline earth metal, and x is the valence of Me.

7. A lubricating oil composition containing lubricating oil and 0.1-3.0%01 a compound having the general formula t I is IA in which R, R1 and R:are alkyl radicals, at least one of which has from 4 to 14 carbon atoms,n is a small whole number less than 3, andm is a small whole number lessthan 3.

ELMER W. COOK. WILLIAM D. THOMAS, JR.

